Coated flatting agent and process for making the same



Patented Nov.

UNITED STATES PATENT OFFICE cos-ran mi-mva AGENT snn'raocsss roa MAKING'rns sum was Aner, Em Orange, N. 1.4mm to mtcrchemlcal Corporation, NewYork, N. Y., a

corporation of Ohio 'No Drawing.

Application August 14, 1941, Serial No. 406,927

'1 Claims. '(cl. roe-'11s) This invention relates to organic flattingagents for use in the preparation of dull coating compositions, and tothe compositions and finished articles containing said flatting agents.

. finishes which are more or less matte and free.

from specular reflection, either for the decorative effect (as infurniture finishes) or for the utilitarian effect (as in finishes forphotographic devices, where a non-reflecting surface is essential). Suchan effect can be obtained by the use of very high percentages of pigment(e. g.

flat wall paints, automobile undercoaters); but it is often desirable toget the same efi'ect withoutloading the film with pigment, eitherbecause the film properties of a lightly pigmented finish are desired,or because a transparent finish' is desired.

To obtain this effect, the coating composition may be designed with anunbalance of the various film-forming ingredients and solvents, so thata portion of the film is precipitated before complete evaporation of thesolvent. A very satisfactory flatting effect may be obtained in thisfashion; by careful compounding with certain classes of ingredients,exceedingly tough, transparent dull films are often obtainable. However,the method is not applicable to those classes of film-forming materialswhichcannot be precipitated and-retain toughness of. film. Furthermore,even with the best flat finishes of this type, the degree of flatnessvaries with the drying conditions, and uniform results cannot beobtained unless drying conditions are maintained absolutely uniform.Because of the difliculties involved in maintaining absolutely uniformdrying conditions, this type of fiat composition is used only inisolated instances.

The trade in general has adopted the use of powders ,whichare'relatively insoluble in the coating compositions, and which can bedispersed therein to yield films which are transparent because of thesimilarity in refractive index between the flatting agents and thefllmforming solids, and are flat because of the fact that the insolubleflatting agents break up the light reaching the surface of the film. Theflat-' classes-inorganic transparent inert pigments, and organicflatting agents.

. The common. inorganic inerts are siliceous materials, such asinfusorial earth, silica, silica gel, some talcs, etc. They areessentially pigments capable of staying on'the surface of coatings whilewet and during film, and which are transparent because their refractiveindices approach those .of the vehicles, and which are able to produceeffective flatting because of the uneven surface so formed. They havethree principal disadvantages. First, they are never perfectlytransparent when a fllm of very low reflectivity is wanted. Second, theysettle very badly to hard dry cakesupon storage. However, this'appearsto be a property associated with their particle size and shape.Finally,-the films produced are essentially pigmentedfilms,

- so that wherehigh flexibility is desired, as in artificial leather,the films are unsatisfactory because they craze on flexing.

- The common organic flatting agents comprise certain transparentuncolored heavy metal since they are more nearly similar in refractiveindex to the film-forming agents. Furthermore,

because of their low specific gravity, and because of their similarityin general constitution to the vehicles, they stay in suspension better,settling into fiocculates which are easily stirred back into uniformdispersions. Because of these advantages, they are preferred fortransparent interior'finishes and the like. They have, however, certainmarked disadvantages. While they do not weaken a film as badly as theinerts, films containing these agents also show crazing when flexed, ason artificial leather, except in the case of the most soluble. soaps,which are extremely diflicult to handle. Certain of the soaps hydrolyzewhen the films are exposed to water, causing an objectionable whiteningof the film.

Finally, the waxes and soaps are all more or less ting agents generallyemployed fall into two to lay in drying of the films, as well invarnishes as in lacquers, and the films formed in humidity have a cheesyappearance.

I have invented an organic fiatting agent of the metallic soap typewhich retains the transparency and non-settling characteristics of thistype of fiatting agent, and at the same time is resistant to hydrolysis,is sufficiently compatible with nitrocellulose films so that crazing onartificial leather is eliminated, and is considerably less soluble thanthe ordinary soaps used as fiatting agents. In the preferred form of{'my invention, the solubility is so lessened that the fiat material canbe used in many baking finishes. This new material comprises a soap ofrosin, the melting point of which has been increased by some reaction(e. g. hydrogenation, combination with phenolaldehyde resin, theDiels-Alder reaction with maleic anhydride, etc), with a heavy metal ofthe group consisting of the alkali earths, magnesium, zinc and aluminum,in the form of a powder of pigment particle size, the individualparticles of which are coated with an originally water-solublefilm-forming material which is insoluble in organic solvents (e. g.methyl cellulose, the filmforming proteins such as albumin, gelatine,etc.. water-soluble urea-formaldehyde resins, water- 'soluble gums suchas dextrin, gum tragacanth,

gum arabic, etc.) preferably converted, if possible, to thewater-insoluble state after being coated on the soap particles. Films ofthe water-soluble urea resins and similar condensation products may beconveniently rendered water-insoluble, after being applied to the soapparticles, by heating for a short eriod of time. The water-solubleproteins, how ver, are most easily rendered insoluble by treatment withformaldehyde or other known hardening agent. The coated maleic-rosinsoaps are especially useful in finishes which are hardened by baking.

The powdered soap may be dispersed in oil, oleo-resinous, resinous,cellulose derivative, rubber and otherfilm-forming compositions. by theuse of ordinary dispersion machinery. The resultant films are more orless flat, depending on the percentage of fiatting agent added; theflatting eifect per unit weight compares favorably with that of theordinary metallic soaps. However, the films are unique in that thetoughness of the original glossy film is more nearly approximated thanwith ordinary soaps; this is particularly noticeable in artificialleathers, where the use of these fiatting agents eliminates crazmg.

I believe that the unusual results obtained are due largely to the useof modified rosin as a base for my new products. Rosin is miscible withpractically all film-forming materials (except where its acidityinterferes), and the heavy metal soaps of rosin are sufficiently likeitself that they are readily soluble in common organic film-formingmaterials and in the common solvents. Therefore, these soaps ofunmodified rosin cannot ordinarily be used as fiatting agents. Evenrosins modified with phenol-formaldehyde, which are less soluble thanrosin itself, yield soaps which are still too soluble for satisfactoryuse as flatting agents. Where the rosin is modified with maleicanhydride, or other acid having the structure necessary for theDials-Alder reaction with rosin (e. g. fumaric acid, citraconic anditaconic anhydrides), the resultant heavy metal soap is sufficientlyinsoluble to be useful as a fiatting agent except in baking finishes.However, I increase the insolubility of all of these modified rosinsoaps without interfering with their compatibility with resinousvehicles (as is evidenced by non-embrittlement and non-crazing thereof)by coating the modified rosin soap particles, as mentioned above,- thusmaking usable in most finishes those modified rosin soaps which areotherwise too soluble, and rendering even more efiective (andtherefore'useful'in baking finishes) those modified rosin soaps whichare insoluble to begin with. At the same time the light fastness offilms flattened with these coated modified rosin soaps is increased.

The rosin may be modified with any of the well known resinous andnon-resinous materials which will combine therewith to yield a modifiedrosin of higher melting point. Preferably, the rosin is modified-with anunsaturated acid of thetype which will enter the Diels-Alder synthesiswith the rosin, for the reasons already mentioned. The rosin may bemodified to any desired degree with these materials, althoughsubstantially complete modification is preferred in order to obtain asgreat an increase in melting point (and often reduced solubility aswell) as is possible.

Satisfactory fiatting agents can be made as follows:.

EXAMPLE 1 Base resin Pounds N wood rosin 300 Maleic anhydride 54 Thematerials were placed in a 200 gallon aluminum kettle, and heated toabout 200 C. in 30 to 60 minutes. The batch was held at 200 C. for about30 minutes, raised to 245 C. in about 30 minutes, and held forcompletion of the reaction for about 30 minutes. The melt was cast atabout 180 C., and broken up. The acid number of the resin was 229 andthe melting point was C.

The resin was then made into a soluble soap, and precipitated with asalt of a heavy metal. A typical procedure is as follows:

Preparation of flattiny agent Thirty pounds of the base resin weresaponified with 9 pounds of sodium hydroxide in 25 gallons of water, atthe boil. A solution of 3 pound of methyl cellulose (medium viscosity)was prepared in 36 gallons of cold water (60 F.). This was added tdthesoap solution, also at 60 F. To this cold solution was added aprecipitating solution of aluminum sulfate, also cold, made bydissolving 26 pounds of aluminum sulfate in 6 /2 galmay occur at highertemperatures). The resultant powdery product was ready for incorporationin a coating composition.

I Exsmu: 2

Example 1 was repeated, by using 36 pounds of maleic anhydride and 300pounds of rosin in making the base resin. The reaction conditionsincreased.

were otherwise unchanged. 'The resulting prod act was a fiatting agentwith somewhat higher solubility characteristics in organic solvents thanthe fiatting agent made according to Example. 1. 7

Instead of decreasing the proportion oi. maleic anhydride to rosin, thesame may be also. further Exnrruii Example 1 was repeated. using thesame base resin but using only half of the sodium hydroxide solution forthe saponification oi the full amount or. the base resin (30 pounds) andalso using half of the aluminum sulfate.- The resulting fiatting agenthad the same proportion of maleic anhydride and rosin as in Example 1,,but the aluminum content of the fiatting agent was reduced,

thereby decreasing the fiatting power and increasing the solubility inorganic solvents.

Besides changes in proportions of maleic anhydride, sodium hydroxide andaluminum sulfate 'with respect to the rosin, the physical properties ofthe products maybe slightly modified by heating the mixture todiil'erent temperatures in making the base resin orin precipitating thecoated aluminum soap oi the base resin. Also, other water-solublealuminum salts may be used instead or aluminum sulfate for theprecipitation, e. g. aluminum acetate.

Zinc, magnesium and alkali earth metals may also be used in place ofaluminum to produce the insoluble soaps.

. Exlulrtr 4 v Flat varnishes, lacquers and other coatings maybeprepared with fiatting agents made according to the present invention.A few examples are given herewith, to showtypical proportions offlatting agent used to get a film with reduced sheen:

A. Lacquers v Percent by weight Flatting agent 6 Nitrocellulose 12 Damarresin 6 Tricresyl prosphate 4 Solvent consisting of 60% toluol, ethylacetate, 10% butyl acetate and 10% butanol I 72 B. varnishes I Percentby weight Flatting agent 7 8 gal. long China-wood oil-modified phenolicvarnish base 2 Mineral spirits 68 C. Alkyd-urea varnish Percent byweight Flatting agent -1 A glyceryl phthalate resin modified with tateand V3 ethyl alcohol e..

incorporated.

\ Exams 5 Base resin N wood rosi 100 Phenol-formaldehyde A-stage resin4.--..- 12

The N wood rosin was heated -to 400 Fsand the A-stage resin addedgradually. reheating the mixture to 400 1!. each time and holding themixture at 400' 1". until the foam sets. Between addition. of thediiferent portions oi'the A-stage resin, it is advisable to waitimtilthe roaming stopsbeiore adding the next portion. After all theA-stage resin has been added, the mixture was heated slowly to'4'l5? F.and held for one hour, cooled to 350 1''. and discharged.

' Preparation of named agent The procedure was the same as thatdescribed in Example 1.

Instead of a liquid A-stage phenol-formaldehyde resin,;arosins'oluble,-solid condensation product of an alkyl-substitutedqlhenoland formaldehyde,- such as'resin made Romp-tertiarybutyl-phenolor-p-tertiary-amyl-phenol, was used.

In making the base resin ofethis example the proportions of rosin tophenolic resin-may be changed, as well as the reaction temperature. Alsoother rosin reactive phenolic may be Example. 1 was repeated with thesole change that ,the methyl cellulose solution was added to the alreadyprecipitated and washed aluminum soap of the maleic anhydride rosinwhich had been washed on a filter press until free or sulfate ions. Thewet cake of the filter press was reintroduced into the precipitationtank, 30 gallons of water were added in addition to" the 36 gallons ofmethyl cellulose solution. The agitator was employed until the metalsoap was freely dispersed in the aqueous medium. The mixture was thenbrought to a boil by introducing steam. into the cold solution. Themixture was heated to boiling for ten minutes, filtered hot. and thefilter cake dried and broken up. In this alternative procedure analready formed soap is coated with methyl cellulose, whereas, in Example1, the coating occurs in situ during precipitation.

If, desired, rosin compounds which are capable of. being saponified (e.g. ester gum) may be substituted for the rosin in the preparation ofthese fiatting agents.

The incorporation oi! the fi atting agent into the various vehicles maybe carrled'out either by preparing a concentrated paste of the fiattingagent in the vehicle or in a solvent mixture, and

then diluting the paste by the addition of further vehicle quantities;or the incorporation may be carried out in a single operation bygrinding the fiatting agent directly the vehicle in the finalproportions. The grinding may be carried out in pebble mills, roller.rnills, or with the aid of other suitable equipment.

The above examples are' illustrations of .the

diflerent embodiments oi the presentinvention. and should not beconsidered as limiting its scope. I claim:

1. A new composition of useful as a fiatting agent which issubstantially transparent in conventional lacquer and varnish films,which comprises pigment size particles oi a soap or a metal of the classconsisting of aluminium, zinc, magnesium and the alkaline earth metals,and rosin which has been modified by chemical reaction to increase itsmelting point while leaving its carboxyl group free to form soaps,coated with a film deposited from an aqueous solution of a water solublecolloidal organic film forming agent which is insoluble in liquidhydrocarbons.

2. The composition of claim 1, i which the melting point of the rosinhas been increased by hydrogenation.

3. Thecomposition of claim 1, in which the melting point of the rosinhas been increased by reacting with a phenol-aldehyde condensationproduct.

4. The compositio of claim 1, in which the organic film forming agent ismethyl cellulose free to form soap, coated with a film deposited from anaqueous solution of a water soluble colloidal organic film forming agentwhich is insoluble in liquid hydrocarbons.

6. Process for making fiatting agents which are substantiallytransparent in conventional lacquer and varnish films, which comprisesreacting rosin to raise its melting point without attacking the carboxylgroup therein, forming an aqueous soap solution thereof, precipitating awater insoluble soap by the addition of a soluble salt of a metal of theclass consisting of aluminium, magnesium, zinc, and alkaline earthmetals, coating said particles by depositing a film thereon from anaqueous solution of a water soluble colloidal organic film forming agentwhich is insoluble in liquid hydrocarbons, and recovering the coatedsoap.

7. Process for making fiatting agents which are substantiallytransparent in conventional lacquer and varnish films, which comprisesreacting rosin to raise its melting point without attacking the carboxylgroup therein,fonning an aqueous soap solution thereof, precipitating awater insoluble soap by the addition of a soluble salt of a metal of theclass consisting of aluminium, magnesium, zinc, and alkaline earthmetals, coating said particles with methyl cellulose which is soluble incold water and insoluble in hot water.

LAszL AUER.

